The present invention relates to a display instrument for aircraft for showing the attitude, particularly the rolling and pitching position or the flight path angle, by means of a "HEAD-UP DISPLAY" or a visual display recording unit showing a symbol and a symbol which is stabilized in an earth-fixed manner for showing the true horizon, as well as symbols for displaying the rolling and pitching angle or the flight path angle.
As a result of increasingly higher flying speeds and therefore also higher accelerations during flying maneuvers in the case of civilian airplanes and particularly also airplanes for military use, and because of an increase of the work to be performed by the pilots since flight systems are becoming more complicated, it is necessary to continuously monitor more and more instruments without losing sight of the outside world.
For a relief, so-called "HEAD-UP DISPLAYS" (HUD) are used by means of which the instrument display is superimposed on the view of the air space which the pilot has in front of him.
The information data required for guiding the flight, such as the pitch angle .theta., the roll angle .phi. and the flight path angle, are recorded in a known manner electronically and are displayed in the form of symbols by means of a cathode ray tube or a correspondingly controlled television system or a noctovision system.
Among the main parts of such systems are a display unit for the pilot; a symbol generator for generating display symbols; and an optical system to project the symbols into the pilots outside field of view symbols into the airplane windshield.
Instrument display values which are important for the guiding of the flight and are to be shown on the "HEAD-UP DISPLAY" are, among others, also those which indicate instrument readings concerning the flight attitude, the compass course or the angle of incidence, by means of numbers or signs, such as dot-type or line-type graduations.
For showing the attitude and for the pilots' spatial orientation, so-called pitch ladders are generally used in all airplanes equipped with "HEAD-UP DISPLAYS" in connection with reference symbols which are stabilized relative to the airplane or relative to the ground. These attitude reference displays are usually moved proportionally to the rolling and pitching speeds of the airplane. However, as the agility of the airplanes increases, it becomes more difficult to interpret such display methods.
It is an object of the invention to improve the attitude orientation for pilots, particularly during highly dynamic flying maneuvers, by means of a stationary representation of the attitude that is easy to interpret while avoiding attitude reference displays which must be moved as a direct function of the airplane pitching or airplane rolling speed.
This object is achieved by providing a display system for aircraft for showing the attitude, particularly the rolling and pitching position or the flight path angle, comprising a windshield projection device (HUD "HEAD-UP DISPLAY") with devices for generating and displaying symbol features representative of the aircraft position in the exterior field of view of the pilot, said symbol features including:
an artificial horizon symbol which is stabilized fixed to earth for displaying the artificial horizon, PA1 a rolling angle symbol representing the aircraft rolling angle, PA1 and one of a pitching angle symbol representing the aircraft pitching angle and a flight path angle symbol representing the aircraft flight path angle, PA1 an airplane symbol which represents the airplane, and PA1 an information symbol having a radial center axis and which changes in size as a function of measured values depending on the rolling position (.phi.) with respect to its angular position or as a function of the measured values depending on one of the pitching position (.theta.) and flight path angle position with respect to its course.
said symbol features comprising:
A display instrument constructed according to the invention permits the creating of symbols or information symbols, which are fixed in a stabilized manner on the airplane and on the ground and which allows a fast intuitive grasping of the respective flying situation or attitude by the pilot, particularly also in the case of high pitching and rolling speeds. In the normal attitude, the information symbol is situated exactly above the attitude symbol represented as a semicircle segment; or as a result of corresponding control movements of the pilot, the airplane can be intuitively returned by the pilot from an attitude deviating from the normal attitude into the normal attitude while he takes into account the change of the information symbol to a sector shape or ring sector shape of a central angle of 180.degree..
The system of symbols according to the invention allows, as an alternative to the display of the rolling and pitching angle, also the display of the rolling and flight path angle .gamma.. In the case of the display of the flight path angle, the segment length (center angle) amounts to 180.degree.-2.multidot.the flight path angle .gamma. (180.degree.-2.gamma.).
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.